To counteract global warming and reach the “double carbon” target,carbon capture,conversion,and utilization (CCCU)is a crucial technical strategy. One of the most recognizable carbon capture techniques,chemical absorption requires a lot of energy toregenerate CO2-loaded solutions. Bio-regeneration of CO2-loaded solutions using hydrogenotrophic methanation was proposed here forreducing carbon capture costs. In this method,a solution with a pH of 10 was prepared with Na2CO3 and microbial nutrient solutions asCO2 absorbents,and hydrogenotrophic methanation was used to convert CO2 to CH4 so that the solution could be regenerated and theabsorbent reused. Initially, a tidal hydrogenotrophic methanation reactor was developed in order to increase the rate of CO2bioconversion. Its viability for bio-regeneration of CO2-loaded solutions was determined after examining its startup performance. Theresults showed that on day 33,the gas residence time (GRT) of the tidal hydrogenotrophic methanation reactor had reached 23 minutes 2and the CH4 content at the reactor outlet was about 95%, indicating a CO2 conversion rate about 10 times higher than that of theconventional trickling bed and fixed bed. During the start-up phase, pH and alkalinity were essentially stable, there was no obviousaccumulation of organic acids,and the average total organic acid concentration ranged from 0.2 to 2.3 mmol/L. In the subsequent 5 cyclesof CO2-loaded solution bio-regeneration experiments, the regenerated absorbent’s mean CO2 uptake was 55 mmol/L with a standarddeviation of 1.1 mmol/L. The pH of the regenerated absorbent remained stable at 9.53±0.05,indicating that a CO2-loaded solution basedon hydrogenotrophic methanation could effectively recycle absorbent. In the reactor,the relative abundance of the alkali-tolerant bacterialgenera Proteiniborus and Acinetobacter and the archaeon Methanobacterium increased after the CO2-loaded solution bio-regenerationexperiment. Results indicate that microorganisms have progressively adapted to weakly alkaline environments by reorganizing theircommunities to conduct metabolic processes such as CO2 methanation.

苗佳慧(1998—),女,新疆乌鲁木齐人,硕士研究生。E-mail:904304408@qq.com

--

MIAO Jiahui,WANG Jiancheng,DAI Yanan,et al. Performance of tidal hydrogenotrophic methanation and its feasibility for regenerating CO2-loaded solutions[J].Clean Coal Technology,2024,30(11):104−111.